Police deployment of sonic blasters at Occupy Wall Street and G-20 protest rallies is fuelling both sales and criticism of the devices, which emit beams of sound with laser-like intensity.

More US police and emergency-response agencies are using the so-called Long-Range Acoustic Devices instead of megaphones or conventional loudspeakers for crowd control, according to news reports and leading manufacturer LRAD Corp. of San Diego.

But the products, which the makers developed as nonlethal options for military use, are prompting outcries from people on the receiving end, who call them “sound cannons.” The city of Pittsburgh is fighting an American Civil Liberties Union lawsuit claiming the piercing tone from a police blaster during the 2009 G-20 summit permanently damaged a woman’s hearing.

At least one Occupy Wall Street protester says New York City police also used the punishing alert tone, although police say they have used the device only to broadcast messages.